Process for the recovery of hydrogen and oxygen by electrolysis



June 23, 1925.

E. BAUR PROCESS FOR THE RECOVERY OF HYDROGEN AND OXYGEN BY ELECTROLYSISFiled Sept. ,2, 1921 plate mw of iron Patented June 23, 1925.,

Emir. sum; or ZURICH, SWITZERLAND.

PROCESS FOR THE RECOVERY-OF HYDROGEN AND OXYGEN BY ELECTROLYSIS.

Application filed September 2, 1921. Serial No. 498,034.

To all whom it may concern:

Be it known that I, EMIL BAUR, residing at 53 Ottikerstrasse, Zurich 6,Switzerland, a citizen of Germany, have invented certain new and usefulImprovements in Processes for the Recovery of Hydrogen and Oxygen byElectrolysis (for which I filed application in Germany May 29, 1920), of

which the following is a specification.

The usual methods of producing hydrogen and oxygen electrolytically aredeficient for two reasons. Because .of the overvoltage, especially atthe anode, there are polarizations of two volts and more even at lowcurrent-densities, and because of the resistance of the usual aqueouselectrolytes, of the polarization by dilution and of increasingover-voltage it is not possible to overcome moderate current-densitiesin the range of size of one ampere per sq. din. By lowering thepolarization to about the value of the reversible voltage of thehydrogenoxygen-cell and b increasing the currentdensity it would bepossible to reduce the expenses for the current and for the cell.

It has now been found that the electrolysis of molten caustic soda orpotash or mixtures of the same, when they contain water, goes on withoutsensible overvoltage, 'though the current-densities are taken very high.Asa fact, it is known, that on electrolysis of water-containing causticsoda hydrogen and oxygen are enerated (of. Leblanc and Brode, Zeitscrift fiir Elektrochemie 1902, pag. 698), but in these experiences onlylittle quantities of hydrogen and oxygen were evolved by an accessoryreaction, hence it cannot be seen, that the gases are formed inacondition suitable for technical purposes. With'reference to .aqueoussolutions it was to presume,that an overvoltage would arise with highercurrentdensities. On the contrary it was found that no overvoltageappears even with very high current-densities. With a current-intensityof ten to twent amperes per sq. dm and with a distance 0 four to fivecm. be tween the electrodes the voltage of the'cell ailixed mysignature.

amounts to only 1,5 volts, so that both energy and space are much betteravailed than in all water-electrolyzers yet known.

The following process for the electrolysis of water is based on thisknowledge:

The accompanying drawing illustrates onev form of, apparatusfor-carrying out the method. I

In thesaidl drawing,

-Figure 1 is a: vertical section.

Figure .2 is a vertical .section at right angles thereto.

Like numerals indicate like parts in the different views.

A square vat 1 of iron-plate contains molten caustic soda or potash witha content of about five to ten per cent of water. The electrolyte isheated to about 250 up to 300. C. A set of small rectangular gasometers2, made of iron-plate, plunge into the fused electrolyte. The gasometerscontain insulated electrodes 4 of iron-plate 5, alternatively connectedwith the positive and negative pole. Out of every gasometer arises a'pie 3 to lead away hydrogen and oxygen. with a stream. of water-vapour,which must be led to the kathodicchambers in the same rate, as theproducts of theelectrolysis escape out of the cell. To roduce thevapour, the heat, carried off by t e gaseous pro nets of theelectrolysis can be used following to the well-known principles ofheaft-regenerat- I ing. The whole electrolytical cell may be surroundedby a heat-insulating cover and a suitable heating-wire, to keep the cellon the needed temperature.

I claim:

A processor method for the recovery of pecial pipes provide thebathhydrogen and oxygen, which consists in electrolyzing with highcurrent-densities molten caustic soda or potash or mixtures of the same,containing water in solution and restoring the water, decomposed. byelectrolysis, substantially as described.

In testimony whereof I have hereunto Pxor'ussos mm. BAUR.

